The present invention relates to an aquaculture system and, in particular, it concerns a system for increasing aquaculture biomass density by aeration using atmospheric air only.
By way of introduction, modem aquaculture is trying to reduce cost of operation and investment in intensive aquaculture facilities by reducing the size of the farm facilities. This is being achieved by creating a relatively small culture volume in which the reared species is cultured at high densities. Such high densities are not common in the natural environment and special means are needed to support the need for dissolved oxygen, degassing of carbon dioxide and removal of solids from the culture water.
The most wide spread solution is to use oxygen enrichment from a liquid oxygen source or from an oxygen generator. The high concentration of the source allows super saturation of oxygen and thus allows a low rate of water recirculation. In this method, high-energy input is needed to dissolve-in the oxygen, as well as to strip off the carbon dioxide created by respiration.
Other methods relying on aeration apparatus such as paddle wheels, surface agitators, and air diffusers, limit maximum bio-density. Bio-density is limited due to the narrow band available for oxygen introduction between saturation and the minimal concentration required for the well being of the reared species. Typically the minimum concentration needed is not far from saturation (1-3 parts per million difference). Bio-density is also limited due to the maximum velocity and turbulence created by such apparatus, limiting its use and creating a maximum density barrier derived from the rate of oxygen consumption and the maximum allowable speed and turbulence.
Therefore, there is a need for a system to surpass the density limitation for an aerated recirculated aquaculture system